Two women were killed and seven other people were injured on Tuesday after a powerful explosion gutted part of a women-only spa complex in an upscale area of Tokyo, officials said.
Only twisted wreckage remained of an annex of the spa, with the walls and ceiling completely blown away.
The blast was reportedly caused by a gas problem in the building that supplies water to Shiespa, a spa that opened last year in Tokyo's bustling entertainment district of Shibuya.
"I've never experienced such a strong impact before," a man who witnessed the blast told a television reporter.
"I thought it was an earthquake at first," he said. "I saw people being carried away from the site. They were so bloody that I couldn't even tell whether they were men or women."
Rescuers dug for hours through the rubble littered around the chic district and by sunset found a woman in her 20s, who is believed to be the last missing victim and was in serious condition.
Deadly accidents are rare in Tokyo, the world's largest metropolis, where strict building codes are meant to ensure that the infrastructure can withstand frequent earthquakes.
Two women, 51 and 22 years old, were confirmed dead in the blast, a fire department spokesman said. The department said earlier they were both in their 20s.
The company managing the spa was pumping up hot spring water at the place of the accident, the Tokyo Fire Department said.
News reports said the blast might have been caused by natural gas that filled the building and caught fire.
A rescuer at the site said it was still not known where exactly the blast had occurred.
"We cannot tell because the floors of the building have completely collapsed," he said.
The explosion took place next to the main spa building, which is nine storeys high.